M20J pilot incurs deviation from assigned altitude due to WX and does not advise ATC of the cause.

Attributes
ACN	523997
Time
Date	200108
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : pns.airport
State Reference	FL
Altitude	msl bound lower : 6900 msl bound upper : 7375
Environment
Flight Conditions	IMC
Weather Elements	Rain Turbulence
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : p31.tracon artcc : zfw.artcc
Operator	general aviation : personal
Make Model Name	M-20 J (201)
Operating Under FAR Part	Part 91
Flight Phase	cruise : level
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : private
Experience	flight time last 90 days : 68 flight time total : 700 flight time type : 240
ASRS Report	523997
Person 2
Affiliation	government : faa
Function	controller : departure
Events
Anomaly	altitude deviation : overshoot altitude deviation : excursion from assigned altitude inflight encounter : turbulence inflight encounter : weather other anomaly
Independent Detector	other flight crewa
Resolutory Action	flight crew : regained aircraft control flight crew : returned to assigned airspace
Supplementary
Problem Areas	Weather Flight Crew Human Performance
Primary Problem	Weather

Narrative:

During level flight at 7000 ft MSL, about 45 mi north of kpns, I penetrated a cloud that was about 3/4 mi in diameter and cumulonimbus in nature. The cloud was not dark and I had penetrated clouds of equal size prior to the event with no altitude deviation. Upon entering this cloud, I got caught in an updraft and severe turbulence. The aircraft climbed to 7375 ft MSL and pulled between 2 -3 G's. My true air speed was 125 KTS. Immediately after exiting the updraft, the aircraft descended rapidly to 6900 ft MSL at greater than -2000 FPM, 1 negative G was pulled. The deviation lasted no longer than 15 seconds. The controller said nothing to me and I know that he was holding a light twin at 8000 ft MSL until we cleared each other. Flight service led me to believe that the major WX would be near birmingham. They had no reports of the turbulence I experienced. I did not issue a PIREP because I did not want to bring attention to my deviation. My flight was from 82J to M91. I was the only person on board. I should have been more aware of the increasingly unstable air mass and asked for more aggressive deviations around the WX. In retrospect I should have given a PIREP to inform other pilots.

Original NASA ASRS Text

Title: M20J PLT INCURS DEV FROM ASSIGNED ALT DUE TO WX AND DOES NOT ADVISE ATC OF THE CAUSE.

Narrative: DURING LEVEL FLT AT 7000 FT MSL, ABOUT 45 MI N OF KPNS, I PENETRATED A CLOUD THAT WAS ABOUT 3/4 MI IN DIAMETER AND CUMULONIMBUS IN NATURE. THE CLOUD WAS NOT DARK AND I HAD PENETRATED CLOUDS OF EQUAL SIZE PRIOR TO THE EVENT WITH NO ALTDEV. UPON ENTERING THIS CLOUD, I GOT CAUGHT IN AN UPDRAFT AND SEVERE TURB. THE ACFT CLBED TO 7375 FT MSL AND PULLED BTWN 2 -3 G'S. MY TRUE AIR SPD WAS 125 KTS. IMMEDIATELY AFTER EXITING THE UPDRAFT, THE ACFT DSNDED RAPIDLY TO 6900 FT MSL AT GREATER THAN -2000 FPM, 1 NEGATIVE G WAS PULLED. THE DEV LASTED NO LONGER THAN 15 SECONDS. THE CTLR SAID NOTHING TO ME AND I KNOW THAT HE WAS HOLDING A LIGHT TWIN AT 8000 FT MSL UNTIL WE CLEARED EACH OTHER. FLT SERVICE LED ME TO BELIEVE THAT THE MAJOR WX WOULD BE NEAR BIRMINGHAM. THEY HAD NO REPORTS OF THE TURBULENCE I EXPERIENCED. I DID NOT ISSUE A PIREP BECAUSE I DID NOT WANT TO BRING ATTN TO MY DEV. MY FLT WAS FROM 82J TO M91. I WAS THE ONLY PERSON ON BOARD. I SHOULD HAVE BEEN MORE AWARE OF THE INCREASINGLY UNSTABLE AIR MASS AND ASKED FOR MORE AGGRESSIVE DEVS AROUND THE WX. IN RETROSPECT I SHOULD HAVE GIVEN A PIREP TO INFORM OTHER PLTS.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.